Question

我在使用以下方法时遇到困难。我无法弄清楚我的问题是否存在，但我已将其缩小到不从文件中填充数组列表。非常感谢任何帮助。

private void searchButtonActionPerformed(java.awt.event.ActionEvent evt) {

//create arraylists
ArrayList<String> model = new ArrayList<String>();
ArrayList<String> length = new ArrayList<String>();
ArrayList<String> width = new ArrayList<String>();
ArrayList<String> radius = new ArrayList<String>();
ArrayList<String> depth = new ArrayList<String>();
ArrayList<String> volume = new ArrayList<String>();
ArrayList<String> shape = new ArrayList<String>();

//fill arraylists from file
try {
    String outputline = "";

    BufferedReader fin = new BufferedReader(new FileReader("stock.dat"));
    while((outputline = fin.readLine()) != null)    {
       // for(int i = 0; i < outputline.length(); i++)    {
       int i = 0;

            //model
            boolean flag = false;
            String pass = "";
            while(flag = false) {
                if(outputline.charAt(i) != ',')
                    pass.concat(Character.toString(outputline.charAt(i)));

                else
                    flag = true;
                i++;
            }
            model.add(pass);

            //length
            flag = false;
            pass = "";
            while(flag = false) {
                if(outputline.charAt(i) != ',') 
                    pass.concat(Character.toString(outputline.charAt(i)));
                else
                    flag = true;
            }
            length.add(pass);

            //width
            flag = false;
            pass = "";
            while(flag = false) {
                if(outputline.charAt(i) != ',') 
                    pass.concat(Character.toString(outputline.charAt(i)));
                else
                    flag = true;
            }
            width.add(pass);

            //radius
            flag = false;
            pass = "";
            while(flag = false) {
                if(outputline.charAt(i) != ',') 
                    pass.concat(Character.toString(outputline.charAt(i)));
                else
                    flag = true;
            }
            radius.add(pass);

            //depth
            flag = false;
            pass = "";
            while(flag = false) {
                if(outputline.charAt(i) != ',') 
                    pass.concat(Character.toString(outputline.charAt(i)));
                else
                    flag = true;
            }
            depth.add(pass);

            //volume
            flag = false;
            pass = "";
            while(flag = false) {
                if(outputline.charAt(i) != ',') 
                    pass.concat(Character.toString(outputline.charAt(i)));
                else
                    flag = true;
            }
            volume.add(pass);

            //shape
            pass = "";
            for(int j = i; j < outputline.length(); j++)
                pass.concat(Character.toString(outputline.charAt(i)));
            shape.add(pass);
        }
    fin.close();
    }
catch(IOException e)    {
    System.err.print("Unable to read from file");
    System.exit(-1);

}

int at = -1;
for(int i = 0; i < model.size(); i++)   {
    if(model.get(i).equals(searchIn.getText())) {
        at = i;
        i = model.size();
    }
}
    Component frame = null;

if(at != -1)    {
    searchDepthOut.setText(depth.get(at));
    searchLengthOut.setText(length.get(at));
    searchRadiusOut.setText(radius.get(at));
    searchVolumeOut.setText(volume.get(at));
    searchWidthOut.setText(width.get(at));

}
else
    JOptionPane.showMessageDialog(null, "Your search did not return any results", "ERORR", JOptionPane.ERROR_MESSAGE);

}

Answer 1

用逗号分隔readline并完成它。我还要为模型，长度，宽度等创建一个对象......然后有一个该对象的arraylist。

while((outputline = fin.readLine()) != null)    {

    String[] tokens = outputline.split(",");
    if(tokens.length == 7){
        SObj o = new SObj; //Some Object

        o.model = tokens[0];
        o.length = tokens[1];
        //and so on

        oList.add(o);
    }
}

Answer 2

除了人们列出的所有其他问题......

String pass = "";
while(flag = false) {
if(outputline.charAt(i) != ',')
   pass.concat(Character.toString(outputline.charAt(i)));

pass是一个String。字符串是不可变的。你想要

   pass = pass.concat(.....)

Answer 3

永远不会运行

while(flag = false) - 它总是评估为false。试试while (!flag)

Answer 4

我建议你重新构建代码。问题不仅在于存在某种解析器错误，而且还很难分辨出发生了什么 - 代码显然是在假设输入行的结构，但是你必须仔细阅读并追踪在你的脑海里重构它的方法。

像

这样的东西

/** Expect a line of the form model, length, ...,
  return a list of ... 
*/
private String[] parse (String inputLine)
{
  //check input line charachteristics-not null, length, ...
  String out=  inputLine.split(",");
  if (out.length()!= ... 
  //whatever sanity checking...

}

private List<String[]> extract(BufferedReader fin)
{
  while((outputline = fin.readLine()) != null) 
 {
    //do something with parse(outputline);
  }
}

有用的事情是将文件读取和行解析分开，这样你就可以看到什么是破坏的，而不是一切都在破坏，很可能是关于代码中隐藏的行结构的假设。它需要4个逗号分隔的整数吗？ 5？如果他们用空格填充怎么样？以空行为前缀？

ArrayLists的问题和读取文件

4 个答案: